Professional snowboarder Chelone "Chilly" Miller, the younger brother of Olympic gold medalist skier Bode Miller, was found dead Sunday of an apparent seizure near Mammoth Lakes, Calif., according to U.S. Snowboarding. He was 29.

Miller, originally from Easton, N.H., who had called Mammoth Lakes home for the past few years, "was found unresponsive in his van in the Mammoth Lakes area," according to the Mono County Sheriff's Office.

The sheriff's office dispatch received a call at 12:45 p.m. Sunday regarding an "unresponsive male" in his van. Local paramedics, the fire department, police department and sheriff's deputies were dispatched to the scene, where upon arrival "it was determined that Mr. Miller was deceased," the statement said.

Mono County Sheriff spokeswoman Jennifer Hansen told ABC News Miller was staying at a friend's house when a friend found him and called 911. It appeared he had been dead for a few hours, she said.

While the sheriff's office said the cause of death is being investigated pending autopsy reports, foul play is not suspected.

Miller had a history of seizures after suffering a major head injury in a 2005 motorcycle accident that placed him in coma for 11 days. U.S. Snowboarding said Miller's fatal seizure Sunday stemmed from that accident.

Recently, Miller had finished fourth in the 2013 Sprint U.S. Snowboarding Grand Prix at Canyons, Utah and had been focusing on snowboardcross to qualify for the 2014 Olympic Winter Games in Sochi, Russia. Just last month, Miller won the Rahlves Banzai Tour overall title with a victory in Sugar Bowl, Calif.

In an interview with The Ski Channel on Monday, Bode Miller, who is an alpine ski racer with the U.S. Ski Team and a two-time overall World Cup champion, said his brother "loved life so much."

"It made him easy to love and easy to be around," Miller told The Ski Channel. "I'm going to miss him a lot."

Both Miller brothers starred in The Ski Channel's film, "The Story." In it, Chelone Miller said as soon as he and his brother learned how to walk, they were put on skis. Around age 9, he said he picked up snowboarding and "immediately fell in love with it."

In a statement on the U.S. Snowboarding website, Bill Marolt, the president and CEO of the U.S. Ski and Snowboard Association, said, "Chelone Miller was an aspiring elite athlete who had made great progress as a snowboardcross rider this past season. We are all deeply saddened at the news of his death and extend our condolences to the entire Miller family."

As news of Miller's death spread, several professional snowboarders, Olympic athletes and fans expressed their condolences.

Pro snowboarder Trevor Jacob, a friend of Miller, posted a tribute on his Facebook page:

"To my friend, brother, and idol. The gnarliest snowboarder is truly an understatement. I could never wrap my head around how truly gnarly you are. Charging first descents truly no one else is skilled or crazy enough to do. Things, no one, in the history of time will probably ever do again, YOU DID IT," he wrote.

Emily Cook, a freestyle skier and two-time Olympian, wrote on Twitter, "Broken hearted to hear of the passing of Chelone Miller. Sending love and prayers to Bode, friends and family."

"My heart goes out to @MillerBode and his family. So sad for the loss of such a great person. #RIPchilly," tweeted Olympic pro snowboarder Elena Hight.